1. Field of the Invention
The present invention relates to a storage apparatus utilizing movements of a movable conductor arranged between electrodes, and a manufacturing method thereof.
2. Description of the Related Art
In recent years, with an increase in an integration degree of a semiconductor device, a circuit pattern of an LSI element constituting this apparatus is further miniaturized. Such pattern miniaturization requires not only a simple reduction in a line width but also an improvement in a dimensional accuracy or a positional accuracy of a pattern. A storage apparatus called a memory is not an exception, and a fixed electric charge necessary for storage must be held in a narrower region in a cell formed by taking advantages of a highly accurate processing technology.
Although various kinds of memories, such as a DRAM, an SRAM, a flash and others have been conventionally manufactured, all these memories use an MOSFET in a memory cell, and hence an improvement in a dimensional accuracy at a ratio exceeding a ratio of miniaturization is required with miniaturization of patterns. Therefore, a large burden is imposed on a lithography technology which forms these patterns, and this is a factor of increasing a product cost (see, e.g., the following references: “Semiconductor Memory; DRAM” in OYO BUTURI Vol. 69, No. 10, pp. 1233-1240, 2000, and “Flash Memory, Recent Topics” in OYO BUTURI Vol. 69, No. 12, pp. 1462-1466, 2000).
On the other hand, as a technology which radically eliminates problems of such miniaturization processing, there is an attempt which artificially synthesizes a desired molecular structure and utilizes homogeneity of obtained molecules to acquire an element having homogeneous characteristics. However, this type of method has a serious problem in a technology of arranging a synthesized molecule at a desired position or acquisition of electrical contact with an arranged electrode. Further, such an element stores information by using a very small number of electric charges, it has a problem that the probability of an erroneous operation due to a disturbance of natural radiation or the like becomes very high.
As described above, in a memory using a conventionally utilized MOSFET for a cell, a dimensional accuracy or a positioning accuracy of a pattern becomes rigorous with miniaturization of a pattern, and there is a factor of increasing a manufacturing cost in addition to a technical difficulty. On the other hand, in a memory utilizing a molecular structure, there is a fear that the probability of an erroneous operation due to a disturbance is large in addition to a problem concerning a manipulation of molecules or contact with an electrode.
Therefore, there have been demanded a highly integrated storage apparatus which is hardly affected by a disturbance and a manufacturing method of a storage apparatus which can manufacture this storage apparatus at a low cost.